SUMMARY OF WORK One primary goal of the laboratory has been to determine the effects of age, gender, lifestyle variables and cardiovascular (CV) disease on cardiac performance, both at rest and during exhaustive dynamic exercise. We have utilized several techniques to accomplish this mission, including determination of maximal aerobic capacity (VO2MAX), blood volume measurements and gated cardiac blood pool scanning. Recent examples of these studies are shown. A. To determine the relative importance of central versus peripheral contributors to the age-associated decline in aerobic capacity, we performed gated cardiac blood pool scans with respiratory gas measurement during exhaustive upright cycle ergometry in 73 healthy BLSA men and women 22-86 years old. Peak cycle aerobic capacity declined 43% between ages 30 and 80, due to a 28% decline in cardiac output and a 22% decrease in arteriovenous oxygen (AVO2) difference. Thus, cardiac and peripheral factors contribute nearly equally to the age-associated decline in aerobic capacity. B. To evaluate CV performance throughout prolonged submaximal endurance exercise (PSE), 17 healthy BLSA volunteers aged 53 +/-5 years performed upright cycle ergometry at 70% of peak VO2. Cardiac volumes were acquired by gated cardiac scans at rest and every 10 minutes during PSE until exhaustion. Although VO2 did not change during PSE at this constant work rate, arteriovenous oxygen difference declined 11% and cardiac output (CO) increased 19% between 10 minutes and end PSE. The CO increase was mediated by a 9% increase in both heart rate and stroke volume and a 7% increase in ejection fraction. Thus, cardiac performance increases progressively during PSE and peripheral factors, rather than cardiac fatigue, limit exercise performance. C. We examined the contribution of leisure time physical activity (LTPA) patterns to the age-associated decline in treadmill peak aerobic capacity (VO2) in 1116 male (n=619) and female (n=497) healthy BLSA subjects 18-95 years old. Although total LTPA was a significant univariate predictor of peak VO2 (r=0.29, p<.001), it accounted for only 1.8% of the variance in peak VO2 per kg.weight after consideration of age and body mass index. D. Follow-up rest and exercise gated cardiac blood pool scans have been obtained in 12 senior athletes initally tested 8-10 years ago. Data analyses are pending at this time.